Kevin S. answered 03/18/13
Margarita -
An angle usually represents a measurement - such as 90 degrees or 1/2 pi radians.
A vertex generally represents the "point" of the angle (or in later cases, a parabola or an ellipse) where the direction changes.
Let's assume you were walking on the lower edge of an equilateral (all sides the same length) triangle, heading towards the left. When you have to turn and start walking up the left edge, AT THAT POINT is the vertex.
Vertices is plural for vertex, just like indices is plural for index. (Gotta love the predictability of the english language)
PS - Don't be embarrassed - I applaud you for wanting to loop back and learn this!
Margarita M.
Kevin, thank you so much for your helpful response - that is totally clear now - and also for your encouragement!
I notice that Wyzant have me registered as living in 'Myrtle, MS', wherever that is! I actually live in the Canary Islands, a Spanish province that is just off the coast of the Western Sahara.... I've asked Wyzant if any of their tutors are willing to work via email. (Do you?) Best wishes, Margarita
03/18/13